Energy matters: presynaptic metabolism and the maintenance of synaptic transmission.

Synaptic activity imposes large energy demands that are met by local adenosine triphosphate (ATP) synthesis through glycolysis and mitochondrial oxidative phosphorylation. ATP drives action potentials, supports synapse assembly and remodelling, and fuels synaptic vesicle filling and recycling, thus sustaining synaptic transmission. Given their polarized morphological features — including long axons and extensive branching in their terminal regions — neurons face exceptional challenges in maintaining presynaptic energy homeostasis, particularly during intensive synaptic activity. Recent studies have started to uncover the mechanisms and signalling pathways involved in activity-dependent and energy-sensitive regulation of presynaptic energetics, or ‘synaptoenergetics’. These conceptual advances have established the energetic regulation of synaptic efficacy and plasticity as an exciting research field that is relevant to a range of neurological disorders associated with bioenergetic failure and synaptic dysfunction. Numerous energy-demanding cellular processes contribute to synaptic activity and function. Li and Sheng describe the mechanisms that regulate presynaptic energy supply to ensure that neurons can meet these demands and maintain their functions during periods of intensive synaptic activity.